Field of the Invention
The present invention relates to wireless communications, and more particularly, relates to a method for transmitting D2D data performed by a terminal in a wireless communication system and a terminal using the method.
Related Art
In an International Telecommunication Union Radio communication sector (ITU-R), a standardization of International Mobile Telecommunication (IMT)-Advanced, which is a next generation mobile communication system after the third generation, has been progressed. The IMT-Advanced is aimed at supporting an Internet Protocol (IP) based multi-media service with a data transmission rate of 1 Gbps in a stop and low speed moving state and a data transmission rate of 1 Gbps in a high speed moving state.
3rd Generation Partnership Project (3GPP) is preparing LTE-Advanced (LTE-A) that improves the Long Term Evolution (LTE) based on an Orthogonal Frequency Division Multiple Access (OFDMA)/Single Carrier-Frequency Division Multiple Access (SC-FDMA) transmission scheme as a system standard satisfying the requirements of IMT-Advanced. The LTE-A is one of the important candidates for IMT-Advanced.
In recent years, there is growing interest in a Device-to-Device (D2D) technology that performs a direct communication between devices. In particular, the D2D is attracting attention as a communication technology for a public safety network. A commercial communication network has been rapidly changed to the LTE but a current public safety network is based on a 2G technology in the aspect of a collision problem with an existing communication standard and a cost. The Request for the technology clearance and an improved service leads to an effort to improve the public safety network.
The public safety network has high service requirements (reliability and security) as being compared with the commercial communication network. In particular, even in the case that the coverage of cellular communication is insufficient or unavailable, there is a need for a direct signal transmission and reception between devices, that is, a D2D operation.
The D2D operation may have various advantages in the fact that the D2D operation is a signal transmission/reception between neighboring devices. For example, a D2D terminal may perform a data communication with a high transmission rate and low delay. Further, the D2D operation may distribute a traffic converged in a base station. In the case that the D2D terminal serves as a relay, the D2D terminal may play the role of extending the coverage of a base station.
Meanwhile, a network may configure a plurality of resource pools that a terminal may transmit a D2D signal, for example, a data (D2D data) according to the D2D operation. In this case, a method may be required for determining which resource pool a terminal uses among the plurality of resource pools.
For example, assuming that there are a first terminal that is going to perform a D2D operation for the public safety and a second terminal that is going to perform a D2D operation for a general data transmission, the case may be required that the first terminal has higher priority between the terminals and performs more reliable D2D communication. Accordingly, a D2D data transmission method and a terminal for it are required.